47-55.1 Drive Line Placement

[dsraven]

check the ranger station for info on the axle and shortening etc. best parts to use and why.

[mick53]

Does it matter if you have more drop? I'm running a Frankland rear end so my pinion is lower.or do I still keep 3 degrees?

[1project2many]

Three degrees is a good safe number although if you really want to get into it there is a lot more that you can do. The higher the angle the more wear on the joint. An angle too low causes brinnelling, which is essentially the rollers beating grooves into the trunion because they never roll.

[mick53]

Thanks for the reply. I'll be running a blown 292 so I will have to revisit this when the time comes. Should have the engine by spring.

[dsraven]

the thing that matters is to match the angles on both ends of the shaft.
a blown 292, that could be interesting. make sure to post pics.

[mick53]

Originally Posted by dsraven

the thing that matters is to match the angles on both ends of the shaft.
a blown 292, that could be interesting. make sure to post pics.

Gaerte Racing Engines just got it back from paint. Global Firethorn red pearl, should have it by spring. Sorry to hijack.

[b-mac]

DS, thanks for the Ranger Stations recommendation.

As many have said, whether view on a vertical or horizontal plane, the angles need to work out.

But, as Mr48 said, I'm probably within range of the U-joints being fine. And this won't be my daily driver/long-haul cruiser.

I'm going to re-measure the angle of the engine to the frame-rails. And, as Joedoh suggested, see if I can shove it a little, or if the engine mount and crossmember need modified to make everything parallel.

This image from Ranger Station explains it pretty well:

[dsraven]

welcome, just trying to help.

[mick53]

Tremec offers this driveline angle app.
http://www.tremec.com/not_am_detalle...le-finder-app/

[b-mac]

Ok gentlemen, to bring this back around with some hard math: I went out and took pictures last night. I mounted the engine only 1" offset to the passenger's side.





The mistake I made, was not matching the transmission mount to this. But, as Joedoh suggested, there might be enough play in the mounts between the urethane, and the block mounting, that I could just slide the tail of the transmission to the right; either by making a new slot in this tab, or I could cut and reweld the landing tab in a slightly different place. This might be this easy, or I might have the remove an reweld engine mounts.

But, by my math, and a few diagrams:



The engine and trans together, from the front of the block to tail housing mount, is 44.5".

My 1" of difference in the front, results in a 1.28732994* angle of the engine from parallel.

Most of what I read, included some of the links here, suggest staying within a 2-degree tolerance for the u-joint angle.

So, based on the above info, do you:

A) Attempt to correct now, whatever rebuilding is required.

or

B) Forge ahead with the build. Get ready to drive. Cross fingers for no issues, and deal with the vibration, if it presents itself later.

???

[mongocanfly]

I'd fix it now... much easier than later...it already looks like your trans mount tab is offset...but moving the tab would be the easiest fix...you need to match the engine angle to the rear diff...what is your rear diff angle at ride height?

[b-mac]

I'm pretty close to 3* down at the engine, 3* up at the rear diff. Difficult to tell without fuel and the wood for the bed, but the 4-link should allow for correcting that.

Explorer 8.8 out back, so the pinion is offset 2" to the passengers side.

Also, the picture you marked on is the modified S10 cross member.
Fortunately/unfortunately, I did do it correctly, and the trans mount is centered between the frame rails. But you make me want to verify.

[mongocanfly]

3down...3up...thats good
Once you get the side2side fixed you should be good...

[joedoh]

if that is your trans mount in the picture I wouldnt slot it, I would just drill a new hole! be done and done. its misleading because you would naturally think moving the one inch required would be right-edge-of-existing hole/one full inch/left-edge-of-new-hole but remember that its one inch center to center of both holes, which there would only be about 1/2 inch between them!

your engine mounting looks perfectly offset, you will not need to modify the engine mounts, there will definitely be that much give in them.

in fact you may not need to change anything at all. the calculation for the angle you have the drivetrain installed is:

theta=tan^-1(height/base), base length is ~35 inches between the two mounts (center of engine mount measured to center of trans mount) and "height" in this case is the 1" the motor is offset, so tan^-1(1/35) is 1.6 degrees. not much angle at all to begin with. even if you moved it over a scant 1/4" by elongating the hole, the angle would reduce to 1.2 degrees, a reduction of 25% (which, unironically, is what you would expect with a 25% reduction in height haha)

if you need a hand lifting grunting drilling or even just hand holding, I will come help!

[dsraven]

everything about engine offsets and such aside. the up angle needs to match the down angle except opposite. the side offset front angle needs to match the offset rear,except opposite. you need an angle finder etc.
do it right the first time and you will be satisfied with the outcome on the road test day. nuthin worse than finding out you have a problem when you are all done.
I've been doing some driveline diagnosis for a nephew with a 1 ton dodge crew cab diesel 4x4 that he installed a lift in. it hasn't been right since the lift went in. the other day he brought it over and we did some math on the driveline angles. installed a 1.5 deg wedge shim under his spring. the vibration was then gone. 1.5 degrees. doesn't seem like much but thats all it took to get rid of the "hum".
a compounded driveline angle is more difficult to get right so easier to match angles now when it isn't loaded down with accesories than later when it's complete and you re getting frustrated. just try to get the angles matched and you should be good. maybe not what you want to hear. your truck, do what you want. just info for you.

[joedoh]

Originally Posted by dsraven

installed a 1.5 deg wedge shim under his spring. the vibration was then gone. 1.5 degrees. doesn't seem like much but thats all it took to get rid of the "hum".

just be devils advocate, his total misalignment may have been more than 1.5 degrees, say 6 degrees up at the rear and 3 degrees down at the trans, and the 1.5 degree shim might have put him back to 1.5 degrees misalignment. zeroing out the angle can wear the joints as bad as misalignment causes vibration.

I have set up a lot of 4 links and I always misaligned them a degree or two based on the advice from the local fast trackers. so 3 down at the trans and 1up at the rear, without vibration.

with leaf springs the misalignment has to be there, because under load the rear will want to point up. drive a truck without a bed and watch the pinion angle swing around. the racers always told me 1-2 for 4 link (tighter bushing, less deflection under load) and 3-5 for leafs.

edit: I had it backwards, pinion will RISE under load. so for leaf springs, 3 down at the trans would be -1 to 0 at the pinion.

[zimspad]

Guys, I have a question regarding drive line angles. Have a 51 that was set up with 3.5" down on the trans and 3" up on the differential. Driveshaft has a 1 degree positive angle from trans to differential meaning the trans is setting a little lower. Thought I had this figured out during mock up but the more I read the more confused I'm getting. I have a slight drive line vibration at highway speeds (could be a number of things, but I've started with checking my angles). I have read that the angles are in relation to the driveshaft and not the horizontal, meaning I need to do a little math to get the true angles. So if the site I'm using is correct, my true angles are going to be -4.5 at the trans and +4 at the differential. Sound right to you, (i actually though that it would be -2.5 at trans and +2 at diff) and if so could 1 to 1.5 degree more than 3 produce a vibration. Also I have read on a number of sites that your pinion should never be angled up due to axle wrap, but that seems to be debatable. Not sure if I should tweek these numbers or move on and look for trouble elsewhere.

[zimspad]

Guess I should clarify that my up and down is from front to back, meaning my tranny tailshaft is pointing down and my differential yoke is pointing up. Seems to be some confusion on that as well when I do research.

[dsraven]

read through this and find your application.
it can also depend on the style of rear suspension and how much flex you get from the leaf springs if that is what you run. spring windup can really affect pinion angle
like said, match the front and rear angles, from the side and from the top. sure, some differences are acceptable but it is also possibly looking for trouble. why vary from the tried and true suggestions laid out by the people who design and manufacture the u joints?
if you are building the driveline from the ground up why not build it right the first time. if using a spring set up that is prone to flex then build in some room for discrepancies. factor in the flex direction under forward power and build in some room for that flexion. understand that if you set up the driveline angles to be perfect when sitting static at ride height then you may get some vibration under heavy load acceleration. that is because the driveline angles can change with pinion angle changes and also can be due to shaft wind up.
get the tooling you need to check the angles properly

https://www.chevyhardcore.com/tech-s...them-in-check/

[dsraven]

https://www.speedwaymotors.com/the-t...t-angles/28855

[MiraclePieCo]

This is a great video illustrating why trans output shaft and pinion angle must be parallel:

https://www.youtube.com/watch?v=gmV4qwLfOMY

.

[zimspad]

Thanks guys, some really helpful information. The Spicer site had probably the most useful information of any that I had visited. And watching the video descibed my exact vibration. I'll spend a little more time in this area and get my total angles down to 3 or under and even them out. Looks like this just might be my issue.

[dsraven]

miracle, I have also posted that video on several different threads here. hopefully it has helped somebody. it seems a lot of fellas don't post it up when something is right after it is fixed, just if there are problems to solve. no biggie, I'm not counting notches on my thumb wrench, lol.

zims, 3 deg is what I would consider to be a max at ride height with possibly some weight added to the seats to simulate a driver/passenger.
the joints need about 1 deg built in so they don't brinnell over time but the biggest thing is to match the angles on both ends of the shafts. up and down and side to side. doing that will cancel the speed fluctuations from the joints. the video is really an eye opener for some. also, like pointed out, if you have leaf springs there can be some spring wrap up which can change the pinion angle on hard accel. especially if a few leaves have been removed for ride height or the spring pack has been swapped out for a softer ride or the suspension bushings are soft to allow the axle to wrap up more. if you are like me, not really a tire burner anymore but appreciate leaving the odd blackie on the tarmac, then try to get the angles matched best for your style of driving. a race car that is always working under extreme driveline load would be a little different than a street car used for cruising to the coffee shop.

[b-mac]

Originally Posted by joedoh

if that is your trans mount in the picture I wouldnt slot it, I would just drill a new hole! be done and done. its misleading because you would naturally think moving the one inch required would be right-edge-of-existing hole/one full inch/left-edge-of-new-hole but remember that its one inch center to center of both holes, which there would only be about 1/2 inch between them!

your engine mounting looks perfectly offset, you will not need to modify the engine mounts, there will definitely be that much give in them.

in fact you may not need to change anything at all. the calculation for the angle you have the drivetrain installed is:

theta=tan^-1(height/base), base length is ~35 inches between the two mounts (center of engine mount measured to center of trans mount) and "height" in this case is the 1" the motor is offset, so tan^-1(1/35) is 1.6 degrees. not much angle at all to begin with. even if you moved it over a scant 1/4" by elongating the hole, the angle would reduce to 1.2 degrees, a reduction of 25% (which, unironically, is what you would expect with a 25% reduction in height haha)

if you need a hand lifting grunting drilling or even just hand holding, I will come help!

Joedoh, such a gentleman. Thanks for the reply, and the offer to help. I may take you up on that. Just checking out all your projects sometime would be inspiring. I'll probably handle it next time the cab comes off, so I'm not doing it from my back. Although, I'm still pondering whether it's necessary. Based on your track guys, if 1 degree off on the horizontal plane is ok, or even encouraged, why not in the vertical plane?

And if you're right, and it will shove enough to make just a new hole in the crossmember fix it, then it could easily be done after the first test drive.

Do you think the rubber trans mounting block will still have enough real estate to land on?

[1project2many]

Based on your track guys, if 1 degree off on the horizontal plane is ok, or even encouraged, why not in the vertical plane?

Mismatch in the horizontal plane is not really encouraged. It's an attempt to set up the driveline so the angles are correct during operation. There are varying amounts of precision guesswork involved and the end result is often angle mismatch. Any time there is mismatch there is vibration so any time a vehicle is operating with mismatched angles, felt or not, there is driveline vibration.